Instantly rising pH

[H20gro]

Hello all. I realize that rising ph is a sign of a problem, but i cant get it to stop rising. I have a single dwc 5 gal w one airstone. Recently, i had a nutrient lockout issue. I resorted to intensive care and was flushing and checking constantly. The plant seems to have recovered (not gotten worse), and was staying fairly stable as far as ph ppm.

Yesterday the ph was high so i flushed and added nutes. Today, ph up again. Ive been tweaking nutes and flushing all day and essentially, as soon as i put ph water in it comes out way higher. Put in at 5.8 and w pump running it comes out 6.8 plus. No matter how many times i flush (it seems). Ive tried stronger ppm nute solution as ive read if its too weak ph will rise. Ive tried straight ph water w no nutes and same happens. Ive put her to sleep for the evening w fresh water but its already 7 ph. Will address as lights come on. Flushing to avoid another nute lockout but dont like her going to bed hungry either.

She is in 6th week of flower, have been using GH flora 3 part. GH ph down and hard tap water. Never a problem in veg, but this is a common occurrence right after the stretch.

Also, im scrogging or i wouldve already swapped out the bucket for a fresh one so i use the liquid transfer pump to get what i can out of res.

Should i just remove scrog screen at this point so i can replace res? Can i re-scrog/net it if i do this?

One pic is yesterday. Other is before the lockout of nutes.

Any help is appreciated!!

 

[JoetheChro]

Hey plants look great, hope you’re well

I know it sounds silly but I made a mistake by not cleaning PH pen, ruined my last grow with complacency, was going in at 4.5 instead of 6.5.

Got some buffering agent and made a very noticeable difference straight away.

Was my own fault, overlooked it and paid for it thinking it was more complicated problems.

I only mention as mine looked the same at 6 weeks/7 weeks

Might just be me not long now til harvest, you’ll get there

 

[Papa OG]

What's your water source?

What's your temp when you check pH?

What's your temp when you refill?

 

[H20gro]

Ok i just removed the scrog net (loosened it) and swapped res out. We will see today what happens. Amos greentree, i calibrated my ph pen and if i measured a fresh bucket w ph water it read 5.8. Move it to water that had just been flushed through at 5.8 and it came out 7 plus. So, i appreciate the input but it didnt seem to be the ph pen.

@Og papa, i use tap water for now. As i mentioned it is quite hard but no probs during veg. Just after stretch as flowering. Hopefully res change will help. The temps have had not affected the readings. I can test fresh water at 70 or the res water at 78, or res water at 70 just as its entered bucket… all same result… skyrocketing ph.
I will say the old res looked pretty dank at the bottom. Likely a lot of undissolved solids/salts etc. hopefully in new res i can get roots (which look good) rinsed of all that gunk too..

Thank yall for your info and assistance. Feel free to send more my way!!!

Im still trying to figure how to tag people. @OGpapa
@Amos Greentree

 

[H20gro]

How about this theory? Either bc of the previous nute lockout or just a natural consequence of dwc growing, or hard tap water, the roots are full of alkaline salts/undissolved solids so its gonna take many flushes and res changes…

May have to go to ro water…

 

[LKABudMan]

What pH down are you using? What type of acid? Phos acid precipitates calcium over time, which can cause it to rise in pH. Have you tried pH some tap water to 5.8, come back a day later and check it. You may just need more pH down.

 

[Papa OG]

I've also heard of some pH down substitutes only being temporary. I know it's painful. But there is probably build up in the roots, or bucket. I would flush, replace. Flush, replace. Maybe 2-3 days straight.

 

[LKABudMan]

I started with GH pH Down (the orange bottle) and that didn't work for me at all. I was adding 10+ml/G and the pH would pop right back up.

I switched to Advanced Nutrients pH Down and have not had any issues since. For my water (100ppm 8.1pH) I add about .75ml/G to get it in the right range. It will still bounce back a little but it stays pretty steady after a small adjustment.

 

[H20gro]

I started with GH pH Down (the orange bottle) and that didn't work for me at all. I was adding 10+ml/G and the pH would pop right back up.

I switched to Advanced Nutrients pH Down and have not had any issues since. For my water (100ppm 8.1pH) I add about .75ml/G to get it in the right range. It will still bounce back a little but it stays pretty steady after a small adjustment.

Thanks. May have to give it a try

 

[Joes Grows]

I have been growing in DWC for a few years and I have found that when my PH goes all crazy, it is usually the air stone or a dirty filter in my compressor. Could also be a starving plant as well. Hope this helps. If you are a smoker, I would check the filter first. I have also found that heat from the compressor will melt the glue in the air stone and push it out of the stone. I start with a new stone every grow, I never re-use them and I only use compressors that I can change the filter in.

 

[H20gro]

I started with GH pH Down (the orange bottle) and that didn't work for me at all. I was adding 10+ml/G and the pH would pop right back up.

I switched to Advanced Nutrients pH Down and have not had any issues since. For my water (100ppm 8.1pH) I add about .75ml/G to get it in the right range. It will still bounce back a little but it stays pretty steady after a small adjustment.

Im using the GH ph down (orange liquid in clear bottle). I have tried to leave it overnight and sometimes see a rise but ive been caught in a vicious cycle of flushing for two days now. Gonna let a bucket sit overnight and will report on that tomorrow. Thanks for your help

 

[H20gro]

I have been growing in DWC for a few years and I have found that when my PH goes all crazy, it is usually the air stone or a dirty filter in my compressor. Could also be a starving plant as well. Hope this helps. If you are a smoker, I would check the filter first. I have also found that heat from the compressor will melt the glue in the air stone and push it out of the stone. I start with a new stone every grow, I never re-use them and I only use compressors that I can change the filter in.

Im actually awaiting arrival of new stone today. We will see thanks for replying and helping

 

[H20gro]

I have been growing in DWC for a few years and I have found that when my PH goes all crazy, it is usually the air stone or a dirty filter in my compressor. Could also be a starving plant as well. Hope this helps. If you are a smoker, I would check the filter first. I have also found that heat from the compressor will melt the glue in the air stone and push it out of the stone. I start with a new stone every grow, I never re-use them and I only use compressors that I can change the filter in.

Regarding your starving plant theory, im looking at the GH feeding schedules for aggressive/medium/light feed… which of those do u think applies to dwc? Either way its a lot different than the bottle’s schedule!

 

[Joes Grows]

I use Advanced Nuts and I feed to what the plant can handle, in my experience not all plants feed the same. 700ppm for one might be great but might turn another into a crispy critter. Some days when I make adjustments, I may check PPM and PH 5 or 6 times per day. As for your question, I would think that light = seedling stage, medium = veg and aggressive = flower but I have never used GH nutes.

 

[H20gro]

What pH down are you using? What type of acid? Phos acid precipitates calcium over time, which can cause it to rise in pH. Have you tried pH some tap water to 5.8, come back a day later and check it. You may just need more pH down.

Would you be able to explain for a dummy, “phos acid precipitates calcium…”?

Or direct me to an explanation via link or??

 

[H20gro]

So i went to the water refill station and got some 20 ppm water at 7+ph. First, it took very little ph down to get it to 5.8. Nothing like the hard tap water.

Mixed in a weak (1/4 strength) nute solution and it stayed stable overnight as did the side bucket w air stone and no plant. Think im just gonna have to use the RO water and spend .50/gallon. But if it works, itll be worth it. For that matter, maybe theres an affordable ro system i can get for the house….. always somethin to spend $ on

hope this solves it

 

[bluter]

So i went to the water refill station and got some 20 ppm water at 7+ph. First, it took very little ph down to get it to 5.8. Nothing like the hard tap water.

Mixed in a weak (1/4 strength) nute solution and it stayed stable overnight as did the side bucket w air stone and no plant. Think im just gonna have to use the RO water and spend .50/gallon. But if it works, itll be worth it. For that matter, maybe theres an affordable ro system i can get for the house….. always somethin to spend $ on

hope this solves it

what's the ppm of the tap water ? there's a good chance the ph down was reacting with calcium creating precipitate. would explain the build up in the res and your ph issues.

if you run RO you will have to add cal-mag back in if you weren't using it before. RO will help keep stuff stable, and is a go to in hydro. i run it in passive hydro.

look in to RO buddy or hydrologic as possible systems. make sure you get a system with a replaceable membrane and filters, they are far cheaper to run. many come with sealed units requiring expensive proprietary cartridges, the replaceable ones can be used with cheap generic filters and membranes.

edit : long term you may also want to check out a chiller for the res.

 

[H20gro]

Im almost embarrassed to say what the tap tds number is…. It works fine for veg and early stretch but then… it gors haywire, so yeah, RO looks to be the answer for now. Good point, @bluter about adding cal/mag. I occasionally added it for my coco plants but less often w the dwc.

I still do not comprehend the precipitating of calcium/ph down, but it does seem to be an explanation. I literally would watch the ph rise as ithe water passed through the bucket, even a clean bucket.

Soooo, to answer your question re: ppm of tds in my tap… FO-FITTY.. yes 450!!! I know i know…. I feel so ashamed. Thought i could get away w it by weaking nutes, especially GH micro, but.. RO IT IS FOR NOW

 

[H20gro]

“Calcium and phosphorus are common essential electrolytes in PN solutions. If mixed in too high a concentration, calcium and phosphorus may form an insoluble precipitate of calcium phosphate.”

@bluter is this the same phenomenon of which you spoke?

 

[bluter]

Soooo, to answer your question re: ppm of tds in my tap… FO-FITTY.. yes 450!!! I know i know…. I feel so ashamed. Thought i could get away w it by weaking nutes, especially GH micro, but.. RO IT IS FOR NOW

you need to be down to 120 or under for most successful dwc / rdwc grows. it is doable on higher numbers depending on nute choice and what is in that 450, and how the other conditions are. it's usually easier just to go RO and control everything yourself.

“Calcium and phosphorus are common essential electrolytes in PN solutions. If mixed in too high a concentration, calcium and phosphorus may form an insoluble precipitate of calcium phosphate.”

@bluter is this the same phenomenon of which you spoke?

yes. the ph up/down, and or a calmag additive, can react with other minerals present to form a precipitate and drop out of suspension.